The purpose of this workshop series is to develop innovative methods of assessing physical activity in preschool age children that can be used in natural environments. The workshop format will draw upon the expertise of internationally recognized scholars and will synthesize expertise from two of the University of Illinois campuses from fields of computer engineering, social media, kinesiology, community health, family health, neuroscience, child development, child care, health disparities, parks and recreation, and public health. Four separate day and 1/2 long workshops will be held over two years to systematically integrate theoretical frameworks across disciplines. Regularly scheduled conference calls will support team building with the goal of collaborative grant submissions. The proposal aims: 1. To develop models of physical activity measurement for diverse groups of children between three and five years of age that can be applied in urban and rural settings. Practical models will be proposed by teams of investigators that can be used for future grant proposals aimed at studying and promoting physical, cognitive, brain, and social-emotional health in vulnerable children (e.g., low income, minority, children with disabilities). 2. To form new partnerships among investigators with expertise in computer engineering, social media, kinesiology, community health, family health, child development, child care, health disparities, parks and recreation, neuroscience, and public health in order to create new measurement techniques of physical activity in young children in their natural environments (home, child care, neighborhoods, parks). 3. To extend the capabilities of existing research and training programs focusing on children's health including a MPH/PhD program (Illinois Transdisciplinary Obesity Prevention Program (I- TOPP), STRONG Kids Obesity Research Program, Fit Kids Afterschool Program, and the Hip Hop to Health Program. Graduate students across several training programs will be included in the workshops and conference calls to promote the next generation of health researchers.